U.S. Pat. No. 5,840,002 discloses a bag having gusseted side panels defined by longitudinal folds and a longitudinal center gusset fold. A scoring apparatus is disclosed to create the longitudinal folds. Diagonal fold lines create a flat bottom.
U.S. Pat. No. 4,273,550 discloses a scoring apparatus for folding a gusseted bag. The bag has folded corner tucks that are unfolded when the bag is expanded.